In many dispensers for the application of solid or semi-solid cosmetic products, in particular, antiperspirant and/or deodorant sticks, there is provided a product-bearing elevator or platform that engages with a threaded screw, the rotation of which moves the platform axially through the barrel to an upper dispensing end from which product is applied. In recent years, dual-walled dispensers in which the product-bearing elevator is contained within an inner barrel or cylinder that, in turn, is contained in an outer shell or jacket, have become increasingly available.
Dual- or double-walled dispensers allow for interesting design features including the possibility of employing translucent or transparent outer shells that allow all or a portion of an inner barrel's colors, graphics, or other visual features to show through the outer shell. The possibility of employing a great many inner barrel/outer shell color combinations significantly expands the potential for customization of branding within the same dispenser configuration.
Where standardizing the dimensions of an inner barrel is of interest, dual-walled dispensers may provide manufacturers with added flexibility in changing the appearance of their packaging, i.e., it may be possible to change the outer shell without having to re-tool the inner barrel. Additionally, dual-walled dispensers provide the potential for an outer shell having more extreme shaping, often desirable from an ergonomic perspective.
Notwithstanding the benefits that they may provide, dual-walled dispensers present several engineering challenges.
A major challenge to fabricators seeking to produce double-walled packs is compensating for dimensional variations, for example, part shrinkage, in a manner that takes into account mating of the inner barrel and outer shell. Dimensional variability may be attributable, in part, to molding conditions and/or tool designs. Part shrinkage issues can be exacerbated by changes to the materials from which dispenser components are molded, such as, for example, changes in color concentrates. Where the same tool is to be used for molding a variety of materials, it is especially critical that the inner barrel/outer shell be configured to provide for part shrinkage and other dimensional variations. Dimensional variations, even when very slight, can result in such components appearing mismatched, interfering with dispenser assembly, and/or impacting functionality and/or visual aesthetics.
To reduce bulk in the assembled dispenser, the inner barrel and/or outer shell of dual-walled packs may have a wall thickness less than that of conventional single-walled packs and, as a result, may be more susceptible to flexing or bending. Additionally, body components of a relatively thin wall thickness can be less resistant to top load fracture or other stresses. Even if individually thinner, joined the strength of such components may be enhanced. Joining the inner barrel and outer shell in a manner that provides acceptable sensory performance, including desirable rotation, can, however, be problematic. Joining of the inner barrel and outer shell is frequently accomplished by the addition of components or pack features, e.g., retention members such as ribs, locks, and the like, that detract from appearance and/or add to assembly cost.
One aspect of this invention is to provide a dual-walled dispense tolerant to dimensional variations, in particular shrinkage of the inner barrel and/or outer shell.
Another aspect of this invention is to provide a robust, double-walled pack having an aesthetically pleasing appearance, wherein the inner barrel and outer shell engage with one another in a manner that resists axial and radial movement that is not otherwise intended, desirably with a minimum number of component parts. Another aspect of this invention is to provide a double-walled dispenser having desirable sensory properties.
These and other aspects of this invention may be achieved by providing a dispenser as hereinafter more particularly described.